The present invention relates to an electrochemical storage device with an electrolyte which forms an ignitable gas and having a housing formed from a tank and a lid joined in a liquid-tight manner to the tank and in which the terminal pillars are passed in a sealed manner through the lid of the housing at the top.
German Utility Model 80 19 159 discloses a storage battery in boxed construction. The housing of the battery is formed from a tank and a lid joined to it in a liquid-tight manner. The terminal pillars are brought out at the top through the lid of the housing in a sealed manner. Incorporated in the lid is a labyrinth-type pressure equalization connection which connects the space situated above the electrolyte and surrounded by the housing to the atmosphere. A monolithic gas displacement body through which the terminal pillars are fed is disposed in the space between the inside surface of the lid and the electrolyte surface. The purpose of the displacement body is to limit the free volume in which an ignitable gas which is formed from the electrolyte can accumulate under certain conditions. The introduction of the displacement body, which is made of an elastic material, is very complicated in terms of production engineering and, furthermore, the elastic material is only compressible to a limited extent in the event of an explosion of the ignitable gas.
An object of the present invention is to provide design an electrochemical storage device which is more advantageous to produce in terms of production engineering and, furthermore, guarantees a better absorption of the pressure waves in the event of an explosion of the ignitable gas.
The foregoing object has been achieved according to the present invention with an electrochemical storage device in which the displacement body is a thin-walled hollow construction to hermetically enclose the cavity it contains. Since the displacement body is formed as a separate, shape-adapted and hermetically closed cavity, the ignitable gas only has a limited volume available. Upon ignition of the gas, the displacement body is able to burst or to be compressed more easily and in larger regions. The volumetric work required for this purpose is drawn from the explosion of the gas. This ensures that, in the case of electrochemical storage devices having, in particular, a plastic housing, the risk of bursting and, consequently, an escape of the electrolyte outside the housing are avoided. Furthermore, production of the device is more advantageous since the displacement body only has t be inserted before welding.